Dental restorative materials are known for restoring the function, morphology and integrity of dental structures damaged by physical damage or caries-related decay of enamel and/or dentin. Dental restorative materials are required to have high biocompatibility, good mechanical properties and mechanical and chemical resistance over a long period of time.
Dental restorative materials include glass ionomer cements having good biocompatibility and good adhesion to the dental hard tissues. Moreover, glass ionomer cements may provide cariostatic properties through the release of fluoride ions. Glass ionomer cements are cured by an acid-base reaction between a reactive glass powder and a polyalkenoic acid. However, conventional glass ionomer cements have a relatively low flexural strength and are brittle due to salt-like structures between the polyacid and the basic glass.
The mechanical properties of glass ionomer cements may be improved by the selection of the combination of the polyacidic polymer and polymerizable compounds in the aqueous dental glass ionomer composition.
WO 03/011232 A1 discloses water-based dental glass ionomer cements mandatory containing two types of polymers, namely a first polymer having a plurality of acidic repeating units but being substantially free of polymerizable vinyl groups, and a second polymer having a plurality of acidic repeating units and a plurality of polymerizable vinyl groups. The dental glass ionomer cement may contain α,β-unsaturated monomers selected from the group consisting of water-soluble, water-miscible or water-dispersible acrylates and methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, glycerol mono- or di-methacrylate, trimethylol propane trimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, urethane methacrylates, acrylamide, methacrylamide, methylene bis-acrylamide or methacrylamide, diacetone acrylamide, methacrylamide, glycerol phosphate monomethacrylates, glycerol phosphate dimethacrylates, hydroxyethyl methacrylate phosphates and citric acid di- or tri-methacrylates.
WO 93/016676 A1 discloses water-based dental glass ionomer cements from β-dicarbonyl polymers. The dental glass ionomer cements contain a polymer comprising i) pendant β-dicarbonyl groups, such as β-diesters, β-diketones or β-ketoesters, capable of undergoing a setting reaction in the presence of water, and a reactive powder, and ii) optionally an ionic group, such as a carboxyl group, capable of undergoing a setting reaction in the presence of water and a reactive powder. Additionally, the dental glass ionomer cements may optionally contain copolymerizable cosolvents such as 2-hydroxylethylmethacrylate or 2-hydroxypropylmethacrylate. In an experimental example, alternatively to these copolymerizable cosolvents, tetraacrylamidomethyl glycouril is contained in the dental glass ionomer cement.